Exercise algebra.equations.quadratic.no-abc

Description
solve a quadratic equation without abc-formula

Derivation

x^2-6*x+9 == 9

⇒ algebra.equations.quadratic.left-square

(x-3)^2 == 9

⇒ algebra.equations.coverup.power

x-3 == 3 or x-3 == -3

⇒ algebra.equations.coverup.onevar.minus-left

x == 6 or x-3 == -3

⇒ algebra.equations.coverup.onevar.minus-left

x == 6 or x == 0